X-ray diffraction (XRD) analysis

PANalytical X'Pert Pro diffractometer, loading sample

X-ray diffraction (XRD) is the primary, non-destructive tool for identifying and quantifying the mineralogy of crystalline compounds in rocks, soils and particulates. Every mineral or compound has a characteristic X-ray diffraction pattern whose 'fingerprint' can be matched against a database of over 250 000 recorded phases. Modern computer-controlled diffraction systems can interpret the diffraction traces produced by individual constituents and highly complex mixtures.

XRD is an essential technique for identifying and characterising the nature of clay minerals, providing information which cannot be determined by any other method.

How does X-ray diffraction work?

  • when monochromatic X-rays are projected onto a crystalline material at an angle (θ), diffraction occurs when the distance traveled by the rays reflected from successive planes differs by an integer(n) of wavelengths (λ)
  • By varying the angle θ, the Bragg's Law conditions [nθ = 2d sinθ] are satisfied by different d-spacings
  • Plotting the angular positions and intensities of the resultant diffracted peaks produces a characteristic pattern
  • where different phases are present, the diffraction trace represents the sum of the individual patterns

Equipment

  • state-of-the-art PANalytical X’Pert Pro diffractometer which can be flexibly configured with flat spinning or capillary stages, 45-position sample changer, temperature/humidity chamber for either routine or research analyses
  • backup Philips PW1700 series diffractometer
  • latest versions of the internationally-recognised ICDD and ICSD databases
  • PANalytical HighScore Plus analytical software including Rietveld refinement for quantification.
PANalytical X'Pert Pro diffractometer
PANalytical X'Pert Pro diffractometer, capillary stage and divergence slits

Applications

The XRD laboratories at Keyworth play a key role in projects that span the BGS science programme, for example:

  • characterisation of lithologies intended for radioactive waste disposal and carbon dioxide capture/storage
  • researching changes in soil clay mineralogy with different land management practices
  • determining the contribution of clay minerals to the engineering behaviour of rocks and soils
  • distinguishing natural and anthropogenic sources of toxic elements in brown field sites
  • providing forensic evidence
  • providing indicators of geological history, basin maturity and low grade metamorphism

Staff and facilities are also in constant demand for direct consultancy analysis and interpretation by external clients including: oil, mineral and mining companies; engineering and utility companies; consultancies; university departments and local authorities.

Contact

Please contact Simon Kemp for further information